1. Field of the Invention
This invention relates to a novel and improved sensor device for measuring a physical parameter at a first location which is remote from a second location. In particular, this invention relates to a sensor device which incorporates fiber optical signal transmission concepts. Still more particular, this invention relates to a temperature transducer and to a position transducer.
2. Description of the Prior Art
During recent years fiber optical signal transmission has become a significant technological innovation in electronic systems. Among the reasons for preference of fiber optical signal transmissions to the former electric signal transmission is the availability of additional bandwidth combined with the elimination of electromagnetic interferences. Other reasons include the convenient separation of the electric potentials of various system components.
Fiber optical transmission has been used for medium and long distance communication and for digital data transmission in certain industry applications where electromagnetic interference or electric separation is of special significance. Fiber optical transmission lines have also been used in connection with high voltage switching, power plant control and process control of electric furnaces. The application in air craft and in automobiles is discussed.
In control systems, signal communication in digital form is performed not only between data processing units, but also between data processing units and input and/or output devices. Special signal sensitivity exists between sensors and data processing devices. Therefore, fiber optical communication on digital basis has been used for signal transmission between sensors and the control and/or processing system (Control Engineering, February, 1979, pages 30-33). The sensor devices serve to acquire input information relative to physical parameters which are of significance for the control and/or processing system, such as temperature, pressure, position, flow, speed, level of liquid, etc.
A sensor device for measuring a physical parameter should combine high accuracy and protection against electromagnetic interference with design simplicity. Such a sensor device should be sturdy and suitable for mass production. In order to keep the costs low, the sensor device should make use of well known and easily obtainable components.